Ski construction



Jan. 25, 1944.

O. RINGNEL SKI CONSTRUCTION Filed June 21, 1941 2- Sheets- Sheet 1 swoontom 05cm Ema/v51,

Jan. 25, 1944. C- RlNGNEL 2,340,080

SKI CONSTRUCTION Filed June 21, 1941 2 Sheets-Sheet 2 FIG. 6.

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z] 1 W e/wbo b 05 CAR F/NGNEL Patented Jan. 25, 1944 UNITED STATESPATENT OFFICE 2,340,080 sxr coNs'raUc'rroN Oscar Ringnel, Ely, Minn,assignor, by meme usignments, to Fern Kingston, Bibbing, Minn.

Application June 21, 1941, Serial No. 399,173 8 Claims. (01. 24 4-408)This invention relates to devices adapted to dynamically contact a fluidor surface such as snow or both during an interval including contactwith snow or a liquid in a first phase and a gas in a second phase.

More particularly, the invention relates to the bottom surfaceconstruction of skis and it is intended for the purpose of thisspecification that the term ski" be generic to airplane runners, sledrunners, the bottom of toboggans, airplane pontoons, hydroplane pontoonsand pontoons generally adapted to be involved dynamically with a liquidsurface.

Prior to the instant invention, airplanes, sleds, toboggans, seaplanesand the like have been equipped with skis, the bottom surfaces of whichhave been more or less flat for contact with a surface such as snow orwater, the forward portion of said skis being generally turned up at thefront to facilitate steering or landing. These prior constructions,however, have not involved any coordinated relation of the axiallyspaced surface portions of the bottom of the ski whereby the efliciencyof same in its dynamic phase will be materially enhanced. In otherwords, the prior art skis were simply designed to effect surface contactalong the main body of the bottom portion of the ski and forfacilitating either landing or steering by the provision of an upturnedportion at the front.

In accordance with the instant invention, it is proposed to use a curvefor the outer surface of skis which is a brachystochrone orbrachystochronic in nature. Such a curve may be defined by the followinginherent property thus: a brachystochrone" or a curve that is brachys-ttochronic in nature passes through a beginning and end point and has alocus along which a dense particle travels the fastest; i. e. if the endpoint is lower than the beginning point, a body following along suchcurve will arrive sooner at the end point than by following any othercurve or straight line. ,Further, in accordance with the instantinvention, it is proposed that the curve of the skis take the form of acycloid, this curve when applied to skis being a "brachystochrone" orbrachystochronic" in nature. Accordingly, skis in accordance with theinstant invention, will force the snow or other particles in which theyglide to take the quickest and easiest path and as a consequence therewill be a minimum of ploughing" such as will detract from the efllciencyof the sliding movement of the ski and applicant has found that he candouble his pay load by changing from conventional skis to skis which arebrachystochronic" in nature. As will be more apparent from the remainderof this specification and the drawings, the particles which are forceddown by the ski travel in accordance with the law of simple harmonicmotion with a characteristic slow start developing into rapid motion andthen gradually diminishing in speed until the particles come to rest.

It is an object of the instant invention to provide a ski having abottom surface of a contour whereby the various portions thereof alongthe longitudinal axis of same will be coordinated in a manner toincrease the efliciency of the ski in its dynamic phase.

It is a further object of the instant invention to provide a relativelysimple ski having a bottom. surface contour-of a high efllclency whilethe ski is in its dynamic phase and which ski construction retains aconventionally upturned forward portion and a generally centrallylocated portion adapted to contact the surface upon which the ski isriding.

It is still a further object of the instant invention to provide a skihaving a specially designed bottom contour of critically highefficiency, both in a first dynamic phase when in contact with snow or aliquid surface, and in a second dynamic phase when moving through a gas,said contour being capableof effecting additional lift" in said firstdynamic phase, so as to obtain maximum "lift reaction from pushing downon the medium involved in said first phase.

Other objects and the nature and advantages .of the. invention will beapparent from the following description taken in conjunction with theaccompanying drawings, wherein:

Fig. 1 is a side elevational view of an airplane equipped with skis inaccordance with the instant invention;

Fig. 2 is a top view of a ski in accordance with the invention;

Fi 3 is a side elevation of the ski shown in Fig. 2;

Fig. 3a is a transverse section taken along line A-A of Fig. 3 andlooking in the direction of the arrows;

Fig. 4 is a view in perspective of a toboggan in accordance with theinvention; and,

Fig. 5 is a fragmentary view of an elevation of an airplane equippedwith a floating ski of the pontoon type. Fig. 5a is a transverse sectiontaken along the line 3-3 of Fig. 5, and looking in the direction of thearrows;

Fig. 6 shows a cycloid or bracbystoechrone of the character to beadapted to the surface of a ski and schematically illustrating themovement of 8. p rticle on the surface thereof in accordance with thelaw of. simple harmonic motion;

Fig. '1 is a schematic lay-out of the surface of a ski in accordancewiththe invention; and,

Fig. 8 is similar to Fig. 7, but more specific as to dimensions.

Referring to Figs. 1, 2 and 3, the airplane I is provided with skishaving an outer covering l2 and an inner frame structure U comprisingangularly disposed tubes. prises a specially curved base sheet l4reinforced at the sides by a pair of split tubes it runninglongitudinally of the base and adjacent the side edges thereof. Thesplit tubes may be spot welded to the base M. The front It of the base Imay be of less width than the central portion l1 and the split tubes i5may follow the inwardly curving contour of the sides of the base Iadjacent the front end l6 of the ski The inner frame structure 3 formedby the tubes involves a pair of triangular braced truss-like formations,each of which may be welded at their base to the upper side of one ofthe split tubes l5 and at their apex to the horizontal cross bar I8.Each of the triangular truss-like formations may comprise the tubes |3aand |3c as best shown in Fig. 3. These truss-like formations are bracedby tubes |3b as shown in Fig. 3a. The connections between the varioustubes and split tubes of the ski inner frame structure and reinforcingmembers for the base sheet of the ski maybe formed by welding or in anyother suitable manner. A top or outer surface I4 of the outer covering|2 may also be formed of sheet metal or other suitable material and thetop curve may be substantially the same as the 'bottom' curve,

differing only at the front and rear portions as will later bedescribed. A fin F to prevent skidding may be secured to the bottom ofthe ski structure as shown in Fig. 3.

The toboggan 30 illustrated in Fig. 4 comprises a base sheet 3| and apair of split tubes 32 adjacent the side edges of the base sheet 3| andextending generally longitudinally thereof. A pair of handles 33 mayextend upwardly from the upper sides of the split tubes 32 adjacent theforward portion 34 of the toboggan 30. The said forward portion includesa nose 35 of generally U-section though the surface contour of the lowerportion of the base sheet 3| is a curve of the same mathematical familyas the curve of the base sheet I4 of the ski The base sheet 3| may beformed with a longitudinally extending opening 3|a to provide for amotorized.

caterpillar tread extending therethrough which may be associated with arotor mounted on shaft 3|b journaled in bearing supports 3|c secured tothe base 3|. The curvature of the bottom of the toboggan acts to tend tolift the toboggan load over the snow while the weightof the caterpillarmechanism acts to retain friction-push" contact with the snow.

Referring to Fig. 5, the airplane 50 is provided with a floating ski 5|of the pontoon type. the bottom'surface 52 of which is of the samemathematical family as the contour of the bottom surfaces of the basesheets l4 and 3| respectively.

The skis 30 and 5| have bottom surfaces and skis II and 5| have topsurfaces of the same mathematical family" which have been found to haveexceptionally high dynamic efliciency in or on the fluid or snow phasefor which they were Each ski comvention/is used for thebottom surfacesof the skis or pontoons or toboggans and the top surdesigned and theyhave been found to have particularly high efllciency whenspeciallydesigned for a succession of phases such as from snow to agaseous phase. The surfaces are formed by a curve of the followingexpression or mathematical formula expressed in parametric form:

a: equals a t-sin 1! equals a (1-cos where a equals the radius of thegenerating .circle and 4: equals the angle formed by the radii passingthrough the point of contact P of the generating circle C (see Fig. 6)which rolls along the line X-X (without slipping) and vertically throughthe line X-X.

The curve generated, Fig. 6, by the circle C is a cycloid and inaccordance with the instant infaces of the skis and pontoons referredto. As a curved surface of this nature is passed over or through amedium such as snow or liquid or gas, an ideal efficiency of dynamiccontact is effected because the particles through which or over whichthe ski is passed are displaced in a manner such that the said particlestend to move in accordance with the laws of simple harmonic motion. Atthe right of Fig. 6, the generating circle is divided into equal anglescorresponding to equal intervals of time. The projections of the radiiforming the angles on the vertical are depicted to illustrate that thedistances from the line X--X to the point where the said radii cut thevertical do not change at a constant rate but rather increase slowly atthe beginning to a maximum rate and then gradually decrease. Thisgradual increase and decrease of the projections correspond to thecurvature of the cycloid so that if the cycloid were moved through adisplaceable medium at a constant rate (corresponding to the constantrate of turning of the generating circle), then the particles of thedisplaceable medium would move with simple harmonic motion.

For practical purposes, the top curve of the skis in accordance with theinstant invention may be similar to'the bottom curve as depicted in Fig.'7 wherein the cross hatched portion schematically depicts a. ski inaccordance with the instant invention.

It has been found in practice, that airplane skis adapted to be used insnow may take the form illustrated in Fig. 8 wherein the majority of theski measured from the forward end corresponds to that portion of thecycloid which is on one side of its axis of symmetry with the remainingor lesser portion of the ski extending on the opposite side of the axisof symmetry. In Fig. 7 the distance from the forward part of the ski tothe axis of symmetry has been denoted by the reference letter A and thedistance from the axis of symmetry to the rear portion of the ski hasbeen denoted by the reference letter B. In Fig.

8, the ratio of A to B is as 62" is to 2'7" when the' total length ofthe ski is 101". As a practical matter, in order to facilitate steeringand general handling of the plane. the tips of the ski may depart from atrue cycloid and may be spiral shaped or the curvature of the bottomsides of the tips may be defined as cycloidal in nature with the radiusof the generating circle decreasing in accordance with the logarithmicdecrement as shown in the drawings. In Fig. 8,.the length of the tipswhich depart from the true cycloid are approximately 6". It is to beunderstood that the ratio of A to B given in Fig. 8 is merelyillustrative and the invention is not to be limited to this ratio asother ratios may be used depending upon the characteristics desired andthe medium over or in which the skis are to be used and thecharacteristics of the body or vehicle associated with the skis. The finin Fig. 8 may be /z" in height and about 6" long. This fin is locatedabout 14" from the rear end of the ski, and is knife-like in section. Itfunctions in a similar manner to the small fin conventionally found onthe bottom of power racing boats.

Wherever curvature is generated either by rolling a wheel on a fixedline, or circle, or by unwinding from a fixed center a thread into atangent line, the ratio of length-speed to (spin) rolling-rate (in 2 pirs or degrees thereof) is ofextreme importance if nuclear-spin-rate tospeedof-light c is fixed because this creates what is called existenceof rate-form of energy called mass, atom or molecule. Further nomolecule exists without its field (-c) and no field exists without itscenter (of whorl-rate) and a field is an energy frequency.

It will be obvious to those skilled in the art that various changes maybe made in this device without departing from the spirit of theinvention and therefore the invention is not limited to. what is shownin the drawings and described in the specification but only as indicatedin the appended claims.

What is claimed is:

1.-A ski having a lower profile formed substantially in accordance withthe following formula expressed in parametric terms:

a: equals a t-sin a) 1: equals a (l-cos 2. The structure recited inclaim 1, the procycloid which extends on the opposite side of and withthe forward portion being longer than the rear portion.

4. A ski formed with upper and lowercycloidal profiles, the lowerprofile at the ends thereof being formed in the shape of a spiraltangent to the cycloid of the lower surface, the ratio of the axialdimension of the spiral shaped ends to the axial dimension of the skibeing approximately as 6 is to 101.

5. A ski having upper and lower profiles oi cycloidal and invertedcycloidal characteristics, the forward portion of said ski extending toa greater dimension from the axis of symmetry of the cycloid forming theprofiles than the dimension from the axis of symmetry. to the rearmostportion of said ski, the lowerprofile of said ski being formed withspirals at the ends which are tangent to the cycloid formin the majorportion of the lower profile of said ski.

6. A ski having upper and lower profiles of cycloidal and invertedcycloidal characteristics,

the forward portion of said ski extending to a greater dimension fromthe axis of symmetry of the cycloid forming the profiles than thedimension from the axis of symmetry to the rearmost portion of said ski,the lower profile of said ski being formed with spirals at the endswhich are tangent to the cycloid forming the major portion of the lowerprofile of said ski, the ratio of the axial dimension of the forwardportion to the axial dimension of the rear portion being approximatelyas 62 is to 27.

7. A ski in accordance with claim 3, the ratio of the axial dimension ofthe 'forward portion to the axial dimension of the rear portion beingapproximately as 62 is to 27.

8. A ski having a lower profile and an upper profile each of which has amajor portion in the form of a brachystochrone as defined by thespecification, whereby when the ski is 'moved through a dlsplac'eablemedium the particles of said medium will be forced aside and caused tomove substantially in accordance with simple.

harmonic motion.

OSCAR RINGNEL.

